1. Field of the Invention
The present invention relates to a power stage for a microscope which is attached to an optical microscope for two-dimensional power transfer of an observation target.
2. Description of the Related Art
A microscope is used in various systems depending on each use in various fields of medicine, biology, industry, etc. Especially, in the industrial field including semiconductor manufacture, automated apparatuses including a microscope have been studied from the early stages in the development to save labor or improve correctness, thereby successfully realizing automated operation and drive units of microscopes.
Thus, a microscope which has been very expensive at the initial stage has been marketed as a less expensive or inexpensive product with an increasing demand.
On the other hand, in the fields of medicine and biology, an automated microscope has become inexpensive with an increasing demand. Thus, the demand for a more operable and inexpensive automated microscope has grown sharply. For example, Japanese Patent Application Laid-open No. Hei 9-120031 describes a capture device and a microscopic image transmission system including: a transferable stage which fixes a test subject; a capture unit for capturing the test subject on the stage transferred to an arbitrary position and outputting a capture signal; an acquisition unit for acquiring absolute coordinates indicating the absolute position of the stage corresponding to the capture signal; a storage unit for storing the absolute coordinates; and a transfer control unit for moving the stage based on the stored value of the storage unit when the test subject is fixed again to the stage.
With the above-mentioned capture device and microscopic image transmission system, the capture unit first captures the test subject on the stage moved to an arbitrary position, and outputs a capture signal. Then, the absolute coordinates indicating the absolute position of the stage corresponding to the capture signal are acquired and stored in the storage unit.
When the test subject is fixed again to the stage, the stage is moved based on the stored value in the storage unit.
Thus, the position of the stage can be correctly specified when the same sample is observed again with the capture device and the microscopic image transmission system.
The stage for a microscope can be positioned while searching for a desired observation point by continuously performing a scanning operation on the plane. On the conventional stage for a microscope there necessarily occurs an error between the amount of drive of a drive unit of a motor, etc. and the corresponding amount of stage displacement. The error is mainly caused by the backlash from the irregularity between the gears configuring a gear train of a power transmission unit.
Although the irregularity between the gears can be reduced by the adjustment of a mechanical structure of the gears, a change with time of the gears, for example, due to the friction during the operation of the stage, inevitably causes a backlash.
The power stage for a microscope is one of the important components of a power microscope. In the system including a power microscope using a personal computer as the center, an operator selects in advance a plurality of observation and measurement points on a sample using a joy stick, a track ball, etc., and temporarily stores the coordinates of their positions so that the operator can automatically perform image processing, a measuring process, etc. on the selected observation and measurement points using the program of the personal computer.
In this case, it is important to eliminate an error between the observation and measurement points selected in advance by an operator and the observation and measurement points in the automatic control.
To remove the influences of the above-mentioned backlash and position selection error, and to suppress an error between the amount of drive of a drive unit and the corresponding amount of stage displacement, Japanese Patent Application Laid-open No. Hei 7-272660 includes: a sample stage loaded with a sample; a sample position detection unit for detecting the position of a sample; a drive unit for moving a sample stage; an operation unit for operating the transfer of a sample stage; and a control unit for controlling a drive unit according to a signal from a operation unit. The control unit is loaded with a sample stage drive apparatus configured to control the drive unit according to a signal of the transfer of a sample from a operation unit and a signal indicating the actual transfer of a sample from a sample position detection unit.
The above-mentioned sample stage drive apparatus controls the drive of a sample stage according to a signal indicating the actual transfer of a sample from a sample position detection unit for detecting the position of the sample, quickly drives the stage which eliminates a backlash, and then correctly moves the stage.
However, Japanese Patent Application Laid-open No. Hei 9-120031 includes a power stage having an acquisition unit for obtaining the absolute coordinates of the current position in the X-Y direction. When a command “Obtain the X-Y coordinates” is issued from a personal computer through an interface, then the power stage obtains the current X and Y coordinates, and returns them to the personal computer through the interface.
The absolute coordinates of the power stage refer to the X-Y coordinates with the mechanical origin of the power stage defined as the coordinate origin. Although not described in Japanese Patent Application Laid-open No. Hei 9-120031, the acquisition unit for obtaining the absolute coordinates of the current position in the X-Y direction requires the configuration of a linear encoder, etc. for detecting the amount of mechanical displacement from the coordinate origin, the velocity, etc. as the amount of electricity in the XY direction of a stage.
That is, since two expensive linear encoders are required, the power stage and the microscope apparatus become very expensive.
Furthermore, since a linear encoder and a detection head for reading the pattern of a linear encoder are attached in the X and Y directions of the stage, the operability around the stage is not preferable when an observing operation is performed.
Japanese Patent Application Laid-open No. Hei 7-272660 requires a linear encoder, a laser interferometer, etc. as a sample position detection unit, thereby producing a very expensive configuration.
Due to the above-mentioned problem, since there occurs a lost motion (movement which is not output by the relationship among idle operations, mechanical rigidity, friction, etc.) from a backlash (idle operations between mechanical elements on the contact surfaces) on any precise mechanism when a desired position of a power stage is stored and the power stage for a microscope is recovered to the position again, the conventional power stage for a microscope has the problem of an error in the recovery position.